42. Trapping Rain Water

Author: benjiwright

csharp/42-Trapping-Rain-Water.cs

@@ -0,0 +1,31 @@
+public class Solution
+{
+
+    public int Trap(int[] height)
+    {
+
+        if (height is null || height.Length == 0) return 0;
+
+        int left = 0, right = height.Length - 1;
+        int leftMax = height[left], rightMax = height[right];
+        var result = 0;
+
+        while (left < right)
+        {
+            if (leftMax < rightMax)
+            {
+                left++;
+                leftMax = Math.Max(leftMax, height[left]);
+                result += leftMax - height[left];
+            }
+            else
+            {
+                right--;
+                rightMax = Math.Max(rightMax, height[right]);
+                result += rightMax - height[right];
+            }
+        }
+
+        return result;
+    }
+}